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TIME OF FLIGHT DIFFRACTION
(TOFD) & PULSE ECHO (PE)
ULTRASONIC INSPECTION OF LPG
SPHEREs
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TOFD Technique
The TOFD technique was first applied in 1985 at the Harwell
Center (UK) in response to insistent requests to size cracks in
nuclear reactor welds.
The TOFD technique is a fully computerized system able to scan,
store, and evaluate indications in terms of height, length, scan,
store, and evaluate indications in terms of height, length, and
position with a grade of coverage, accuracy and speed not achieved
by other ultrasonic techniques.
The TOFD technique is based on diffraction of ultrasonic energy
from tips of discontinuities, instead of geometrical reflection on
the interface of the discontinuities.
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This phenomena makes TOFD effective for identifying cracks and
lack of fusion located along the vertical axis of the weld (in
particular for narrow gap preparation) or with any other
orientations, because defect detection is not affected by
unfavourable orientation to the primary sound energy angle.
TOFD Technique
unfavourable orientation to the primary sound energy angle.
These features have extended the use of TOFD to replace
Radiography and complex Ultrasonic inspection by tandem technique
wherever planar defects (cracks, lack of fusion) are the main
object of examination.
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Four different types of waves are involved in the construction
of a TOFD image:
longitudinal wave generated by the transmitter and partially
transformed in spherical wave when the beam crosses the tip of a
defect
Principle of TOFD
of a defect
the lateral wave that propagates near the surface between the
two transducers
the longitudinal wave reflected by the backwall
the shear waves generated by the mode conversion L/T on the
interface of discontinuities
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Principle of TOFD
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Integrity NDT Ltd have designed and built I-Scan; a simple to
use and versatile semi-automated scanner for TOFD or Phased
Array.
Easy slide, spring loaded probe arms.
Super-strength magnetic wheels.
Integrity NDT I-Scan Scanner
Super-strength magnetic wheels.
Optional positional guide track
Integral positional encoder.
Lightweight robust design.
Cost & time savings through efficient scanning.
More accurate repeatable scanning.
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ADVANTAGES OF TOFD & PE ULTRASONIC INSPECTION
FOR LPG SPHEREsFOR LPG SPHEREs
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LPG sphere remains in-service.
No surface preparation before inspection.
In-Service Inspection
If the spheres paint is well adhered, Integrity NDT can carry
out the inspection on the painted surface.
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Integrity NDT has qualified personnel from the the Industrial
Rope Access Trade Association (IRATA).
Rope Access
Association (IRATA).
Not necessary to build scaffold for reaching your spheres
welds.
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TOFD & PE inspection has better detection and measurement
sensitivity than manyconventional NDT methods (for detailed
Better Detection Sensitivity
conventional NDT methods (for detailed information please look
at the attached academic articles).
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Tank in-service during inspection No down time. No blasting and
preparation cost
Cost Efficiency
No blasting and preparation cost No scaffold cost
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Rapid scanning is possible and weldmentscan be made in a single
pass. This makes the technique more efficient and faster.
Time Efficiency
the technique more efficient and faster.
1000m Tank can be scanned in 4 5 days
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Safety
TOFD & PE outside sphere inspection is safer than accessing
internal sphere surfaces and utilisingconventional NDT inspection
methods.
All of the Integrity NDT Ltd. equipment designed All of the
Integrity NDT Ltd. equipment designed for decreasing the spark
potential.
NDT and Rope Access personnel have safety education.
Integrity NDT Ltd. has safety procedures for decreasing the risk
of the accidents.
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TOFD & Pulse echo ultrasonic inspection on a LPG sphere -
TUPRAS Krkkale Refinery / Turkey
TOFD inspections on North Sea installation process pipework for
weld root erosion - Shell UK.
TOFD inspections on in-service Stainless Steel Chemical Mixing
Vessels onbehalf of Chemtura Chemicals
Recent References
behalf of Chemtura Chemicals
TOFD inspections of pressure vessels for the Khursaniyah
redevelopment project Kingdom of Saudi Arabia for Aramco.
Development of Inspection Management Software Database
development for controlling shutdown inspection activities to
British Energy Plc.
TOFD inspections of high pressure steam pipework at Qurayyah and
Ghazlan power plants Kingdom of Saudi Arabia carried out as part of
asset life management program by ERA Ltd.
TOFD inspections of Liquid Chlorine vessels at Ineos Plc,
Runcorn, UK.
Shutdown Management and Audit of inspection activities during
planned shutdown maintenance at International Power CCGT sites.
References can be provided on request.
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PLEASE CONTACT US FOR DETAILED INFORMATION
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Head Office
Address: Lismore, Well Lane, Mollington, Cheshire, United
Kingdom CH1 6LDTel. +44 (0) 1244851904E-mail:
[email protected]
Contact Us
E-mail: [email protected]
Turkey Branch
Workshop Address: Merkez Sanayi Sitesi 573. sok. No:7 Ivoksan
/Ankara / Turkiye
Grkem Bayten : +90 [email protected]
zgen Bulut : +90 [email protected]
